Delivery Devices.
Formulations such as cosmetics and pharmaceuticals can be dispensed in a wide variety of vehicles and forms, including powders, capsules, liquids, aerosols, and the like. In particular, the delivery of formulations by the aerosol route is generally considered to take one of three forms: (1) the use of “space sprays”, such as spray insecticides and air fresheners, which produce very fine sprays capable of evaporating rapidly or floating in the air; (2) the use of sprays such as hair sprays and deodorants, that are intended for continuous film formation; and (3) the use of aerated foams, such as shaving creams, which are produced by the rapid expansion of a propellant through an emulsion.
A variety of dispensers have been described for the purpose of delivering formulations of these various types. See, e.g., H. Mintzer, “Aerosols”, Chapter 10 in Pharmaceutical Dosage Forms-Disperse Systems, Marcel Dekker, Inc. pp. 204–220 (1989). Aerosols for oral and nasal therapy are generally said to incorporate medicaments as solids suspended in a propellant. More recent advances in valve and propellant technology are said to provide improved delivery to the throat and nasal areas. Formulations delivered in aerosol form by the use of such devices can often include the use of surfactants. For instance, surfactants are commonly used in nebulizer vehicles to decrease surface tension and thus affect particle size (Mintzer, above, p. 206).
Yet other types of aerosol containers, pressurized with nitrogen, have been used to dispense toothpaste through a dip tube and foam-style valve. For a variety of reasons, however, such containers have not been commercially successful. See, e.g., D. Garlen, “Toothpastes”, Chapter 14, pp. 511–532 in Pharmaceutical Dosage Forms-Disperse Systems, Marcel Dekker, Inc. 1989. As a result, various forms of “pump” dispensers have been developed for delivering toothpaste, the pumps relying on the use of a spring device to force the toothpaste out of a spout.
Surfactants
On a separate subject, a large number of surfactants, including sodium lauryl sulfate (“SLS”), have been widely used and found safe in a variety of cosmetic products, including dentrifices. See, e.g., “Surfactants in Oral Hygiene Products”, pp. 299–347 in Surfactants in Cosmetics, M. Reiger ed., Marcel Dekker, Inc. 1985.
As of 1992, SLS itself was present in over 500 oral solid dosage forms approved by the FDA, as well as in 11 oral liquid dosage forms, 38 topical creams, lotions, ointments, medicates sponges or shampoos, and 28 dentrifices. CRC Handbook of Food, Drug and Cosmetic Excipients, S. Smolinske, pp. 359–362 (1992). The usefulness of sodium lauryl sulfate as a synthetic detergent in toothpaste has been studied in a recent article by P. Barkvoll. (“Should toothpastes foam? Sodium lauryl sulfate—a toothpaste detergent in focus”, Norske Tannlaegeforenings Tidende 99(3)82–4 (1989)).
U.S. Pat. Nos. 4,657,758 and 4,666,708, for instance, describe dental rinses for loosening plaque and preventing plaque build-up. The rinses described in both patents rely on the detersive effect of oral surfactants. The '708 patent describes the use of SLS as one such oral surfactant, and further describes its function as a “potentiator” for other ingredients. In the Examples, patients were instructed to use one tablespoon of various rinses. Such rinse products, which are commercially available under the brand name “Plax”, are typically swirled in the mouth in order to produce a weak foaming action.
Chemical Agents.
On yet another subject, there exist a number of useful chemical agents that, for one reason or another, have not previously been prepared in the form of a foamable composition, or delivered in the form of a foam or aerosol spray.
Natural sea water, for instance, has long been thought to provide certain desirable, including healing, qualities. See, for instance, Richard Russel, A Dissertation on the use of Sea Water in the Diseases of the Glands: Particularly the Scurvy. Jaundice. King's Evil, Leprosy and the Glandular Consumption, Preface (pages i–xii), (1769). Rarely, however, is sea water packaged and used for such purposes. This may be due to the present inability of the art to reproducibly prepare and package sea water in a stable form suitable for such use.
Hydrogen peroxide, for instance, is a common ingredient in mouthwashes and gargles. (See, e.g., “Mouthwashes and Gargles”, p. 1680, in American Hospital Formulary Services—Drug Information 1992, G. McEvoy et al. eds., American Society of Hospital Pharmacists). Hydrogen peroxide functions as a weak antibacterial agent, a wound cleanser and a deodorant. It also serves a mechanical effect of effervescence and resultant removal of tissue and other debris.
When used as an oral topical, however, hydrogen peroxide is typically administered in the form of a concentrate, solution, or gel. The product is used for cleansing minor wounds, or minor gum inflammation resulting from dental procedures, orthodontic applications, denture irritations, accidental injury and other mouth and gum irritations (e.g., canker sores).
Such beneficial uses of hydrogen peroxide include its use as an oral germicide, cleansing agent and hemostat. It is considered a useful disinfectant for mucous membranes because of its low toxicity. See, e.g., Zinner. D. D., et. al.; Controlled Study of the Clinical Effectiveness of A New Oxygen Gel on Plaque. Oral Debris and Gingival inflammation, Pharmacol. Ther. Dent., October 1970, 1:7–15.
Dental products such as “MentaDent”, which was recently introduced by Chesebrough-Ponds, relies on the use of hydrogen peroxide. The commercial product identifies related U.S. Pat. Nos. 4,687,663, 4,964,539, 5,020,694, 5,038,963, 5,059,417, and Design patent No. D 315,496. Such patents relate variously to the use of a hydrogen peroxide component with a second component containing sodium bicarbonate; to a dentifrice composition containing, inter alia, hydrogen peroxide and a polyoxyethylene-polyoxypropylene copolymer; to multi-cavity or multi-chamber dispensing containers; and to a design for a dispensing container.
SLS and hydrogen peroxide have, on occasion, been used together in formulations for the oral cavity. See, for instance, U.S. Pat. Nos. 5,104,644 and 5,174,990 (mouthrinse), U.S. Pat. Nos. 5,084,268 and 5,208,010 (tooth whitening dentifrice).
An application previously filed naming the present inventor, and having U.S. Ser. No. 08/218,796, filed Mar. 28, 1994, discloses a system for delivering a chemical agent-containing formulation in the form of a foam, the system comprising a propellantless dispenser containing a foamable formulation comprising the chemical agent in the form of a solution or stable suspension and an aqueous solution of an anionic surface active agent as a foaming agent. Applicant has since found that such dispensers are less preferred, and in many cases unsuitable for such purposes, for a variety of reasons. These reasons include the fact that such dispensers are often subject to mechanical failure, particularly when subjected to agitation or external pressure changes, resulting in the production of inadequate foams.
As a result there continue to be few, if any, instances of the use of devices for the aerosol delivery of formulations to the oral cavity in the form of foams, particularly for formulations that incorporate hydrogen peroxide or sea water, or formulations for use in the oral cavity.